DIAGNOSIS AND SPATIAL VARIABILITY OF SOIL FERTILITY AND CROP PRODUCTION IN EASTERN PARÁ STATE

Abstract

The objective of this study was diagnose and to produce spatial variability maps of soil fertility attributes and production in a teak (Tectona grandis) plantation through geostatistics. The study was conducted on a commercial farm in the city of Capitão Poço, state of Pará, Brazil. Soil and yield data were collected from 155 sampled georeferenced points. The collected soil samples were submitted to laboratory analysis to obtain the values of the following variables: pH, organic matter (OM), calcium (Ca), magnesium (Mg) and potassium (K), available phosphorus (P), aluminum (Al), Base sum (BS), cation exchange capacity at pH 7.0 (T), effective cation exchange capacity (t), base saturation (V%) and aluminum saturation (m %). After that, a diagnosis of the fertility status of the study area was made based on laboratory results. The fertility results and the tree volume were submitted to univariate statistical analysis and geostatistics for the production of spatial variability maps. The soil fertility diagnosis showed K, OM and P as the most limiting parameters in the commercial teak plot. All soil fertility and teak volume variables showed spatial dependence, which enabled the production of spatial variability maps, and their spatial dependence indices were considered strong for most of them. The values of P, K and OM are correlated to the increase in teak volume. The variability maps showed a relationship between available P and volume. Spatial variability maps enable precise interventions in a production teak area.